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bpo-46887: Work around clang MSAN bug on stat()/fstat() #31633

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bpo-46887: Work around clang MSAN bug on stat()/fstat() #31633

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6 changes: 6 additions & 0 deletions Modules/posixmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2484,6 +2484,12 @@ posix_do_stat(PyObject *module, const char *function_name, path_t *path,
STRUCT_STAT st;
int result;

# if __has_feature(memory_sanitizer)
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It requires a check if __has_feature is defined

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pyport.h defines _Py_MEMORY_SANITIZER for us, taking care of all of the compiler/platform conditionals around this.

// bpo-46887: Work around clang MSAN bug:
// https://github.com/llvm/llvm-project/issues/54131
memset(&st, 0, sizeof(st));
# endif

#ifdef HAVE_FSTATAT
int fstatat_unavailable = 0;
#endif
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14 changes: 13 additions & 1 deletion Python/fileutils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1166,6 +1166,13 @@ _Py_fstat_noraise(int fd, struct _Py_stat_struct *status)
status->st_ino = (((uint64_t)info.nFileIndexHigh) << 32) + info.nFileIndexLow;
return 0;
#else

# if __has_feature(memory_sanitizer)
// bpo-46887: Work around clang MSAN bug:
// https://github.com/llvm/llvm-project/issues/54131
memset(status, 0, sizeof(*status));
# endif

return fstat(fd, status);
#endif
}
Expand Down Expand Up @@ -1225,6 +1232,11 @@ _Py_wstat(const wchar_t* path, struct stat *buf)
errno = EINVAL;
return -1;
}
# if __has_feature(memory_sanitizer)
// bpo-46887: Work around clang MSAN bug:
// https://github.com/llvm/llvm-project/issues/54131
memset(buf, 0, sizeof(*buf));
# endif
err = stat(fname, buf);
PyMem_RawFree(fname);
#endif
Expand Down Expand Up @@ -2093,7 +2105,7 @@ join_relfile(wchar_t *buffer, size_t bufsize,
const wchar_t *dirname, const wchar_t *relfile)
{
#ifdef MS_WINDOWS
if (FAILED(PathCchCombineEx(buffer, bufsize, dirname, relfile,
if (FAILED(PathCchCombineEx(buffer, bufsize, dirname, relfile,
PATHCCH_ALLOW_LONG_PATHS))) {
return -1;
}
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